This is an application for a Mentored Clinical Scientist Development Award (K08) with a study focus on juvenile bipolar disorder. Bipolar disorder is one of the most incapacitating psychiatric illnesses and is associated with high rates of morbidity, disability, and suicidality. While it has been recognized since Kraepelinian times that bipolar disorder can have an onset in childhood, the scientific literature addressing its form in childhood and adolescence is scant. Preliminary work suggests that children with bipolar disorder present with severe irritability, mixed presentation with major depression, and chronic course. Impairment is severe and psychiatric hospitalization is common among these children. A leading source of diagnostic confusion in prepubertal mania is the high rate of comorbidity and symptomatic overlap with attention deficit hyperactivity disorder (ADHD). Because distractibility, impulsivity, hyperactivity and emotional lability can be present in both ADHD and bipolar disorder, the differential diagnosis can be difficult. The fact that children with BPD frequently meet criteria for ADHD has created several nosological questions: Are these children very severe cases of ADHD? Is their ADHD a misdiagnosis due to overlapping symptoms? Do they truly have both disorders? During the Award period, the candidate will pursue a Research Plan, undertaking comprehensive assessments of bipolar children, adolescents, and their family members in an effort to distinguish the course, characteristics and comorbidity of juvenile bipolar disorder. Based on pilot work, the candidate proposes to use a family-genetic study to test hypotheses about the nosological validity of BPD+ADHD as a distinct subtype of child psychiatric disorder. The candidate will assess and compare 50 children with BPD+ADHD (age<=12), 50 adolescents with BPD+ADHD, 50 adolescents having BPD w/o ADHD, and 50 non-BPD, non-ADHD pediatric controls, as well as the first degree relatives of each group. The candidate plans to directly interview children and adolescents with bipolar disorder in order to verify and describe the complex clinical picture and developmental variations associated with this diagnosis. In addition to the Research Plan, the candidate plans to pursue coursework and tutorials in research design, biostatistics, genetics, quality of care and quality of life research, and psychiatric epidemiology. This, in addition to mentoring and consultation with senior researchers in child, adolescent and adult psychiatry, will comprise an organized program of training and research aimed at furthering the candidate's personal development towards becoming an independent investigator.